Heat treatment apparatus

ABSTRACT

The present invention is a thermal processing unit including: a heating-furnace body whose upper end has an opening; a reaction tube consisting of a single tube contained in the heating-furnace body; a gas-discharging-unit connecting portion formed at an upper portion of the reaction tube, the gas-discharging-unit connecting portion having a narrow diameter; a substrate-to-be-processed supporting member for supporting a substrate to be processed, contained in the heating-furnace body; and a heating unit for heating the substrate to be processed supported by the substrate-to-be-processed supporting member. The heating unit has: a first heating portion arranged around the reaction tube, a second heating portion arranged around the gas-discharging-unit connecting portion, a third heating portion arranged around an upper portion of the reaction tube, a fourth heating portion arranged around a lower portion of the reaction tube, and a fifth heating portion arranged under the substrate-to-be-processed supporting member.

FIELD OF THE INVENTION

The present invention relates to a thermal processing unit that issuitable for a thermal process to an object to be processed such as asemiconductor wafer.

DESCRIPTION OF THE RELATED ART

Conventionally, in a semiconductor manufacturing process, there is astep of depositing a thin film or an oxide film onto a surface of asemiconductor wafer as an object to be processed, or a step ofconducting a diffusion of impurities onto the surface. For these steps,a thermal processing unit such as a CVD unit, an oxide-film forming unitor a diffusion unit has been used.

In such a thermal processing unit, a plurality of wafers, which areobjects to be processed, are placed on an object-to-be-processed holdingmember called a wafer boat in a vertical arrangement, and then loaded ina reaction tube called a process tube that has been heated to a hightemperature. Then, a reaction gas is introduced into the reaction tube,so that a thermal process to the wafers is conducted (JP Laid-OpenPublication No. 2001-210631 and JP Laid-Open Publication No.2001-156005).

FIG. 10 shows an example of vertical thermal processing unit that hasbeen conventionally used.

In FIG. 10, a heating-furnace body 1001 is placed on a base plate 1011.A resistance heater 1007 is provided on an inside surface of aheat-insulating layer of the heating-furnace body 1001.

A reaction tube (process tube) is provided in the heating-furnace body1001. The reaction tube is surrounded by the resistance heater 1007. Thereaction tube has a double-tube structure of an outer tube 1003 a, whoseupper end is closed, and an inner tube 1003 b installed concentricallyto the outer tube 1003 a. The reaction tube is adapted to keep itsairtightness, in order to form a processing space for conducting aprocess to wafers that are objects to be processed. The outer tube 1003a and the inner tube 1003 b are made of, for example, quartz.

Respective lower ends of the outer tube 1003 a and the inner tube 1003 bare supported by a tubular manifold 1013 made of stainless steel or thelike. A reaction-tube lower lid 1004 is provided for hermeticallysealing a lower opening of the manifold 1013, the reaction-tube lowerlid 1004 being freely opened and closed.

A rotational shaft 1014 is rotatably inserted at a central portion ofthe reaction-tube lower lid 1004 via a magnetic-fluid seal 1015 in sucha manner that the airtightness of the reaction tube is maintained. Alower end of the rotational shaft 1014 is connected to a rotatingmechanism of an elevating mechanism 1016. An upper end of the rotationalshaft 1014 is fixed to a turntable 1017. A wafer boat 1008(substrate-to-be-processed supporting member), which is a holding toolof objects to be processed, is mounted on the turntable 1017 via aheat-insulating cylinder 1012. A plurality of silicon wafers W areplaced on the wafer boat 1008 in a tier-like manner. The wafer boat 1008is made of, for example, quartz.

A or more gas-introducing pipes 1005 are horizontally arranged at alower portion of the manifold 1013 in order to introduce a process gasfor a wafer process into the inner tube 1003 b of the reaction tube. Thegas-introducing pipes 1005 are connected to a gas-supplying source, notshown, via a mass flow controller, not shown.

A gas-discharging pipe 1006 connected to a vacuum pump, not shown, isconnected to an upper portion of the manifold 1013 in such a manner thatthe process gas is discharged from a gap between the outer tube 1003 aand the inner tube 1003 b to set a pressure in the reaction tube at apredetermined reduced pressure.

Herein, recently, it has been requested to enhance throughput of asemiconductor manufacturing unit, and various improvements have beenachieved.

In order to enhance throughput of a semiconductor process without havingany effect on film quality of a surface of the semiconductor wafer, thegreatest possibility is to shorten times of the preliminary heating stepand the cooling step. Then, in order to shorten the times of the steps,it is necessary to shorten the heating time and the cooling time. Forthat purpose, it is necessary to reduce thermal capacity of each memberin the heating furnace in order to achieve rapid heating and rapidcooling.

However, in the conventional thermal processing unit, since the reactiontube has the double-tube structure, the thermal capacity thereof islarge. Thus, the conventional thermal processing unit is not suitablefor rapid heating and rapid cooling.

In addition, it is difficult to uniformly heat the reaction tube havingthe above structure. Thus, improvement of uniformity of the temperatureof a silicon wafer within a surface thereof, which is a substrate to beprocessed, has been desired.

In addition, if the reaction gas introduced into the reaction tubedoesn't react but reaches a ceiling part of the inner tube 1003 b whosetemperature is relatively low, the reaction gas may be deposited on theceiling part, which may cause generation of particles.

Thus, the conventional thermal processing unit can not satisfy therecent request of: enhancing the throughput of a semiconductormanufacturing unit, making uniform the heated temperature of thesubstrate to be processed, and preventing the particle contamination.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a thermal processingunit suitable for rapid heating and rapid cooling in which unevenness inheating an object to be processed such as a silicon wafer is improved.

Another object of the present invention is to achieve a thermalprocessing unit wherein temperature control is easy and wherein particlegeneration is effectively prevented.

This invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member; whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member.

According to the present invention, since the reaction tube consists ofa single tube and has a smaller thermal capacity, rapid heating andrapid cooling of a substrate to be processed are possible. In addition,unevenness in heating the substrate to be processed is remarkablyimproved.

For example, the first heating portion may be formed by a plurality oflinear heat-generating members, which are arranged in parallel with alongitudinal direction of the reaction tube. Alternatively, the firstheating portion may be formed by a plurality of U-shaped heat-generatingmembers, which are arranged in parallel with a longitudinal direction ofthe reaction tube.

In addition, the second heating portion may be formed by a linearheat-generating member, which is arranged in a spiral pattern.

In addition, the third heating portion may be formed by a linearheat-generating member, which is arranged in a spiral pattern.Alternatively, the third heating portion is formed by a linearheat-generating member, which is arranged in a switchback pattern.

In addition, the fourth heating portion may be formed by a linearheat-generating member, which is arranged in a spiral pattern that isseen as a rectangular in a circumferential direction of the reactiontube. Alternatively, the fourth heating portion may be formed by alinear heat-generating member, which is arranged in a switchbackpattern.

In addition, the fifth heating portion may be formed by a plate-likeheat-generating member. Alternatively, the fifth heating portion may beformed by a heat-generating member arranged along a lower surface of thesubstrate-to-be-processed supporting member.

In the above description, the linear heat-generating member may beformed by sealing a resistance heater into a hollow tubular member madeof ceramics. On the other hand, the plate-like heat-generating membermay be also formed by sealing a resistance heater into a hollowplate-like member made of ceramics. Thus, impurity contamination thatmay be caused by a material of the heat-generating member is notgenerated in the thermal processing unit. Herein, it is preferable thatthe ceramics is quartz.

In addition, it is preferable that the second heating portion issupported in a movable manner in a horizontal direction. In the case,assembling operation of the thermal processing unit and/or insertingoperation and removing operation of the reaction tube into and from theheating-furnace body for maintenance may be carried out very easily.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; and a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; wherein the substrate-to-be-processedsupporting member has: a ceiling plate, a bottom plate, and a pluralityof columns connecting the ceiling plate and the bottom plate; a pole forsupporting the substrate-to-be-processed supporting member is fixed to acentral portion of the bottom plate; and grooves for supporting thesubstrate to be processed are formed on the plurality of columns.

According to the above invention, the substrate-to-be-processedsupporting member having a smaller thermal capacity can be easilymanufactured.

Preferably, the pole is formed by a hollow member made of quartz. In thecase, it is easier to process the pole, and impurity contamination isless.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; and a temperature measuring unitformed by sealing a plurality of temperature measuring members into ahollow tubular member.

According to the above invention, by using the result measured by thetemperature measuring unit, more suitable temperature control can beachieved.

Preferably, the hollow tubular member is a quartz tube. In the case,impurity contamination that may be caused by the temperature measuringmembers may be prevented.

For example, the temperature measuring unit may be arranged in avicinity of the heating unit.

In addition, for example, the hollow tubular member may be rotatablyinserted through the reaction-tube lower lid into the reaction tube. Thehollow tubular member may be rotatably and removably supported withrespect to the reaction-tube lower lid. In addition, the hollow tubularmember may be removably supported with respect to thesubstrate-to-be-processed supporting member. In the case, the hollowtubular member may be removed suitably, depending on situation, forexample in assembling the thermal processing unit, in setting up thethermal processing unit or in normally operating the thermal processingunit.

In addition, preferably, the substrate-to-be-processed supporting memberis adapted to horizontally support a plurality of substrates to beprocessed, and a portion of the hollow tubular member can be located ina gap between the plurality of substrates to be processed supported bythe substrate-to-be-processed supporting member.

In addition, preferably, the hollow tubular member has a branchedportion, and the plurality of temperature measuring members is alsoarranged in the branched portion.

In addition, preferably, the hollow tubular member has: a verticalportion extending upward along an inside wall of the reaction tube, abend portion bent from the vertical portion at an upper portion of thereaction tube, and a horizontal portion extending horizontally from thebend portion. When a large number of substrates to be processed aresupported, it is preferable that temperatures at an upper position, amiddle position and a lower position of the substrates to be processedare adapted to be measured.

In the case, more preferably, the hollow tubular member further has: abranch portion branched from the vertical portion at a middle portion ofthe reaction tube in a longitudinal direction, and a second horizontalportion extending horizontally from the branch portion.

In addition, preferably, the hollow tubular member is arranged in a gapbetween the heating-furnace body and the reaction tube. In the case too,when a large number of substrates to be processed are supported, it ispreferable that temperatures at an upper position, a middle position anda lower position of the substrates to be processed are adapted to bemeasured.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; a first temperature measuring unitformed by sealing a plurality of temperature measuring members into afirst hollow tubular member; a second temperature measuring unit formedby sealing a plurality of temperature measuring members into a secondhollow tubular member; and a third temperature measuring unit formed bysealing a plurality of temperature measuring members into a third hollowtubular member; wherein at least a portion of the first hollow tubularmember extends horizontally from a middle portion of the reaction tubein a longitudinal direction; at least a portion of the second hollowtubular member extends horizontally from an upper portion of thereaction tube; and at least a portion of the third hollow tubular memberis arranged in a gap between the heating-furnace body and the reactiontube.

According to the above invention, since the reaction tube consists of asingle tube and has a smaller thermal capacity, rapid heating and rapidcooling of a substrate to be processed are possible. In addition, inmanufacturing the thermal processing unit, in setting up the thermalprocessing unit, in a steady operation of the thermal processing unit,in a maintenance operation thereof, in adjusting the thermal processingunit, or the like, temperature measurement with high precision and highaccuracy is possible, so that more suitable temperature control can beachieved.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; a second temperature measuring unitformed by sealing a plurality of temperature measuring members into asecond hollow tubular member; and a third temperature measuring unitformed by sealing a plurality of temperature measuring members into athird hollow tubular member; wherein at least a portion of the secondhollow tubular member extends horizontally from an upper portion of thereaction tube; and at least a portion of the third hollow tubular memberis arranged in a gap between the heating-furnace body and the reactiontube.

According to the above invention, since the reaction tube consists of asingle tube and has a smaller thermal capacity, rapid heating and rapidcooling of a substrate to be processed are possible. In addition,especially in a steady operation of the thermal processing unit,temperature measurement with high precision and high accuracy ispossible, so that more suitable temperature control can be achieved.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; and two holes formed respectively atan upper portion and a lower portion in a gap between theheating-furnace body and the reaction tube; wherein a cooling medium isintroduced from one of the two holes and discharged from the other ofthe two holes in order to cool the reaction tube.

According to the above invention, throughput of the thermal processingunit is improved.

In addition, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody; a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member; a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube; a second temperature measuring unitformed by sealing a plurality of temperature measuring members into asecond hollow tubular member; and a third temperature measuring unitformed by sealing a plurality of temperature measuring members into athird hollow tubular member; wherein the heating unit has: a firstheating portion arranged around the reaction tube, a second heatingportion arranged around the gas-discharging-unit connecting portion, athird heating portion arranged around an upper portion of the reactiontube, a fourth heating portion arranged around a lower portion of thereaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member; at least a portion of thesecond hollow tubular member extends horizontally from an upper portionof the reaction tube; and at least a portion of the third hollow tubularmember is arranged in a gap between the heating-furnace body and thereaction tube.

Alternatively, the invention is a thermal processing unit comprising: aheating-furnace body whose upper end has an opening; a reaction tubeconsisting of a single tube contained in the heating-furnace body; agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter; a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in theheating-furnace-body; a heating unit for heating the substrate to beprocessed supported by the substrate-to-be-processed supporting member;a reaction-tube lower lid that seals a lower portion of the reactiontube and holds airtightness in the reaction tube; a first temperaturemeasuring unit formed by sealing a plurality of temperature measuringmembers into a first hollow tubular member; a second temperaturemeasuring unit formed by sealing a plurality of temperature measuringmembers into a second hollow tubular member; and a third temperaturemeasuring unit formed by sealing a plurality of temperature measuringmembers into a third hollow tubular member; wherein the heating unithas: a first heating portion arranged around the reaction tube, a secondheating portion arranged around the gas-discharging-unit connectingportion, a third heating portion arranged around an upper portion of thereaction tube, a fourth heating portion arranged around a lower portionof the reaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member; at least a portion of thefirst hollow tubular member extends horizontally from a middle portionof the reaction tube in a longitudinal direction; at least a portion ofthe second hollow tubular member extends horizontally from an upperportion of the reaction tube; and at least a portion of the third hollowtubular member is arranged in a gap between the heating-furnace body andthe reaction tube.

According to these inventions, since the reaction tube consists of asingle tube and has a smaller thermal capacity, rapid heating and rapidcooling of a substrate to be processed are possible. In addition,unevenness in heating the substrate to be processed is remarkablyimproved.

Preferably, a temperature controlling unit is provided around thegas-discharging-unit connecting portion. Thus, particle generation atthe gas-discharging-unit connecting portion can be effectivelyprevented. For example, the temperature controlling unit is aheat-insulating material. Alternatively, the temperature controllingunit is a resistance heater. It is preferable that the temperaturecontrolling unit has flexibility or that the temperature controllingunit is shaped in advance.

For example, the gas-discharging unit is a gas-discharging pipe whoseend portion has a flange, a flange is formed at an end portion of thegas-discharging-unit connecting portion, and the flange at the endportion of the gas-discharging-unit connecting portion and the flange atthe end portion of the gas-discharging pipe are hermetically connectedto each other by means of a sealing unit. In the case, it is preferablethat the temperature controlling unit has a fluid hole provided in theflange.

In addition, it is preferable that the gas-discharging-unit connectingportion is bent. Thus, effect of radiation heat from the reaction tubeto the gas-discharging pipe is inhibited, so that temperature control ofthe gas-discharging-unit connecting portion and the gas-discharging pipebecomes easier.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a thermal processing unitaccording to a first embodiment of the present invention;

FIG. 2 is a schematic view showing a heat-generating member in a spiralpattern used in the thermal processing unit of the first embodiment,FIG. 2( a) is an enlarged partial view of FIG. 1, FIG. 2( b) is a topplan view of the spiral heat-generating member of FIG. 2( a);

FIG. 3 is a schematic perspective view showing a heat-generating memberin a switchback pattern used in the thermal processing unit of the firstembodiment of the present invention;

FIG. 4 is a schematic view showing a heat-generating member in a flatspiral pattern used in the thermal processing unit of the firstembodiment, FIG. 4( a) is an enlarged partial view of FIG. 1, FIG. 4( b)is a right side elevation view of the flat spiral heat-generating memberof FIG. 4( a);

FIG. 5 is a schematic sectional view showing a thermal processing unitaccording to a second embodiment of the present invention;

FIG. 6 is a schematic sectional view showing a main part of the thermalprocessing unit for explaining movement of a temperature measurementmember (device) in the second embodiment of the present invention;

FIG. 7 is a schematic sectional view showing a thermal processing unitaccording to a third embodiment of the present invention;

FIG. 8 is a schematic sectional view showing a thermal processing unitaccording to a fourth embodiment of the present invention;

FIG. 9 is a schematic sectional view showing a main part of the thermalprocessing unit of the fourth embodiment of the present invention; and

FIG. 10 is a schematic sectional view showing a conventional thermalprocessing unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, embodiments of the present invention will be described withreference to the attached drawings.

First Embodiment

FIG. 1 is a schematic sectional view showing a thermal processing unitaccording to a first embodiment of the present invention. The thermalprocessing unit of the embodiment comprises: a heating-furnace body 1whose upper end is open; a heating-furnace lid 2 arranged at an upperportion of the heating-furnace body; and a reaction tube 3 whose mainpart is arranged in the heating-furnace body 1. The heating-furnace lid2 has a hole through which a narrow-diameter portion of the reactiontube extending from an upper portion of the reaction tube 3 can beinserted. A reaction-tube lower lid 4 is provided at a bottom openingpart of the reaction tube 3 in order to maintain airtightness in thereaction tube 3. Substrates to be processed W such as silicon wafers areadapted to be held by a substrate-to-be-processed supporting member 8,which is adapted to be arranged in the reaction tube 3. The substratesto be processed W such as silicon wafers are adapted to be heated by aheating unit 7.

In the thermal processing unit of the present embodiment, an upper endof the heating-furnace body 1 has an opening part. The opening part iscovered with the heating-furnace lid 2. A central portion of theheating-furnace lid 2 is provided with an opening part. On the otherhand, the upper end of the reaction tube 3 protrudes to form agas-discharging-pipe connecting portion 6. Thus, after the reaction tube3 is arranged in the heating-furnace body 1, the gas-discharging-pipeconnecting portion 6 penetrates the opening part of the heating-furnacelid 2 so that the heating-furnace body 1 is covered with theheating-furnace lid 2. Preferably, the heating-furnace lid 2 is formedby combination of a plurality of dividable members.

It is preferable that a cylindrical heat reflector is provided on aninside-wall surface of the heating-furnace body 1. For example, the heatreflector is made of aluminum. The inside surface of the heat reflectoris formed as a mirror surface, which inhibits heat dissipation ofradiant heat from the heating unit, which is described below. Acooling-medium way such as a cooling-water way may be formed in a coilpattern in the heat reflector. The cooling-medium way may be formed as awide space, instead of a thin channel.

(Reaction Tube)

The reaction tube 3 arranged in the heating-furnace body 1 is a singletube made of ceramics such as quartz glass or silicon carbide. Thereaction tube 3 has: a bottom opening part, a reaction-tube cylindricalportion 3 a surrounding the substrate-to-be-processed supporting member,a narrow-diameter portion 3 b located at an upper portion thereof, abend portion 3 c bent at an angle of about 90 degrees above thenarrow-diameter portion 3 b, and a gas-discharging port 6 extending in aradius direction of the reaction tube 3 from the bend portion 3 c fordischarging a reaction gas or the like. Under the reaction tube, areaction-tube lower flange 3 d is formed in order to secure airtightnessto the reaction-tube lower lid 4. At least one reaction-gas introducingpipe 5 is arranged in the reaction-tube lower flange 3 d. A reaction gasfor processing the substrates to be processed such as semiconductorwafers is adapted to be supplied from the reaction-gas introducing pipe5.

In addition, a manifold made of stainless steel or the like may bearranged at a lower portion of the reaction tube 3. In the case, thelower opening part of the reaction tube 3 and the manifold arehermetically connected by means of an O-ring or the like. In the case,the reaction-gas introducing pipe may be inserted through a side wall ofthe manifold. In addition, the reaction-tube lower lid 4 may beconnected to a lower portion of the manifold via an O-ring. Thus,airtightness in the reaction tube may be maintained.

(Substrate-to-be-processed Supporting Member)

In the reaction tube 3, a substrate-to-be-processed supporting member 8made of ceramics such as quartz is arranged. Thesubstrate-to-be-processed supporting member 8 is called a wafer boat,and holds a plurality of, for example about 126, substrates to beprocessed W such as semiconductor wafers horizontally, at the sameintervals (pitches) in a vertical direction. The wafer boat has aceiling plate 8 a, a bottom plate 8 c, a plurality of columns 8 bfixedly jointing the ceiling plate 8 a and the bottom plate 8 c, and asupporting body 8 d fixed to a central portion of the bottom plate 8 c.Grooves are formed on each column, in order to hold horizontally thesubstrates to be processed. These grooves are adapted to supportperipheral edge portions of the substrates to be processed W.

Then, the supporting body 8 d is connected to a rotational shaft of arotation driving unit 10 through a sealing unit 11 such as amagnetic-fluid seal arranged at a central portion of the reaction-tubelower lid 4. Thus, the substrate-to-be-processed supporting member 8 canbe rotated during the thermal processing step.

The substrate-to-be-processed supporting member 8, the reaction-tubelower lid-4, the sealing unit 11 and the rotation driving unit 10 areconnected to an elevating mechanism not shown, so that thesubstrate-to-be-processed supporting member 8 can be taken out from thereaction tube 3. The substrates to be processed W can be placed on thesubstrate-to-be-processed supporting member 8 at a position wherein thesubstrate-to-be-processed supporting member 8 is taken out from thereaction tube 3.

(Heating Unit)

The heating unit 7 consists of: a first heating unit (a first heatingportion) 7 a arranged around the cylindrical portion 3 a of the reactiontube 3, a second heating unit (a second heating portion) 7 b arrangedaround the narrow-diameter portion 3 b of the reaction tube 3, a thirdheating unit (a third heating portion) 7 c arranged around an upperportion of the cylindrical portion 3 a of the reaction tube 3, a fourthheating unit (a fourth heating portion) 7 d arranged around a lowerportion of the cylindrical portion 3 a of the reaction tube 3, and afifth heating unit (a fifth heating portion) 7 e arranged under thesubstrate-to-be-processed supporting member 8 in the reaction tube 3.Hereinafter, each heating unit is explained in detail.

(First Heating Unit)

The first heating unit 7 a consists of a plurality of linearheat-generating members (devices), which are arranged around thecylindrical portion 3 a of the reaction tube 3 and in parallel with alongitudinal direction of the reaction tube 3. Specifically, a largenumber of linear heat-generating members are arranged at intervals ofseveral centimeter orders. Instead of the straight linearheat-generating members arranged in parallel with a longitudinaldirection of the reaction tube 3, a plurality of U-shaped linearheat-generating members may be arranged to surround the reaction tube 3.

The linear heat-generating member is a linear flexible resistance heaterof a high purity material. Herein, a carbon wire formed by twisting (braiding) a plurality of strands of carbon fibers of about 10 μm indiameter is arranged in a ceramics tube such as a straight quartz tubehaving an outside diameter of ten-some millimeters. The end portions ofthe ceramics tube are sealed so as to be connected to outside terminalsfor electric power supply.

Such a linear heat-generating member is superior in dynamic temperaturecharacteristics since it has only a small thermal capacity. Thus, rapidheating and rapid cooling are possible, and control thereof is easy.

The first heating unit 7 a is operated by electric power controlled by acontrolling unit not shown. At that time, the same electric power may besupplied to the whole first heating unit 7 a. However, the first heatingunit 7 a may be divided into a plurality of groups, and respectivedifferent electric power may be supplied to the respective groups tocontrol respective heat values of the respective groups.

The plurality of groups of the first heating unit 7 a may be operatedboth in any series circuit and in any parallel circuit.

(Second Heating Unit)

The second heating unit 7 b is arranged around the narrow-diameterportion 3 b of the upper portion of the cylindrical portion 3 a of thereaction tube 3. Specifically, as shown in FIGS. 2( a) and 2(b), thesecond heating unit 7 b has a structure wherein a linear heat-generatingmember is wound in a spiral pattern. Such structure can increase heatvalue per unit volume.

The second heating unit 7 b is arranged at a plurality of positionsaround the narrow-diameter portion 3 b of the reaction tube 3, in orderto heat a central portion of an uppermost substrate to be processed Wsupported by the substrate-to-be-processed supporting member 8. An areaabove the central portion of the uppermost substrate to be processed Wsupported by the substrate-to-be-processed supporting member 8 is nearto the gas-discharging port 6, which discharges the gas from thereaction tube 3, and far from the first heating unit 7 a. Then,temperature of the area may easily fall. Thus, for example, the secondheating unit 7 b of a spiral pattern is arranged to heat the centralportion of the uppermost substrate to be processed W supported by thesubstrate-to-be-processed supporting member 8, so that unevenness oftemperature within the surface of the substrate to be processed may beimproved.

A terminal connected to the spiral heat-generating member is located outof the heating-furnace body 1, and is adapted to be supplied electricpower from a controlling unit not shown.

The above heat-generating member of a spiral pattern may be formed by acarbon wire that is a resistance heater, which is arranged in a tubemade of a material having electrical insulating properties and heatresistance properties, such as quartz, similarly to the linearheat-generating member of the first heating unit 7 a. The materials ofthe tube and the resistance heater are not limited to quartz and carbon,but may be materials having substantially the same functions.

It is preferable that four heat-generating members of a spiral patternare arranged at four positions around the narrow-diameter portion 3 b ofthe reaction tube 3. In the case, it is preferable that one of the fourheat-generating members is movable in a horizontal direction.

In the case, there is no obstacle in an assembling operation of thethermal processing unit or in a disassembling operation thereof formaintenance.

(Third Heating Unit)

A plurality of third heating units 7 c are arranged so as to surroundthe upper portion of the cylindrical portion 3 a of the reaction tube 3.Specifically, each third heating unit 7 c may have a structure wherein alinear heat-generating member is bent in a switchback pattern as shownin FIG. 3, or a structure wherein a linear heat-generating member iswound in a spiral pattern as shown in FIGS. 2( a) and 2(b). In anexample shown in FIG. 3, electric power supplying terminals 32 areconnected to the both ends of the linear heat-generating member 31. Itis preferable that the third heating unit 7 c is formed by a carbon wireheater contained in a quartz tube as well as the first and secondheating units 7 a and 7 b.

By arranging the third heating units 7 c, unevenness in heating theupper portion of the reaction tube 3 may be improved.

(Fourth Heating Unit)

A plurality of fourth heating units 7 d are arranged so as to surroundthe lower portion of the cylindrical portion 3 a of the reaction tube 3.Specifically, each fourth heating unit 7 d may have a structure whereina linear heat-generating member like the linear heat-generating memberof the first to third heating unit is wound in a flat spiral pattern asshown in FIGS. 4( a) and 4(b), or a structure wherein a linearheat-generating member is bent in a switchback pattern as shown in FIG.3.

By arranging the fourth heating units 7 d, heat dissipation from thelower portion of the reaction tube 3 is prevented, and hence temperaturefall of an lowermost substrate to be processed W supported by thesubstrate-to-be-processed supporting member 8 is prevented. Thus, it ispreferable that the fourth heating units 7 d are arranged under thebottom plate of the substrate-to-be-processed supporting member 8.

The concrete shape of each fourth heating unit 7 d and/or thearrangement number of the fourth heating units 7 d may be suitablydesigned based on thermal calculation.

(Fifth Heating Unit)

The fifth heating unit 7 e is arranged in order to prevent heatdissipation downward from the bottom plate of thesubstrate-to-be-processed supporting member 8 arranged in the reactiontube 3, and hence temperature fall of the lower portion of thesubstrate-to-be-processed supporting member 8. For the purpose of theabove, for example, the fifth heating unit 7 e consists of a plate-likeheat-generating member having a disk shape, or a plate-likeheat-generating member formed by arranging a heat-generating memberalong the bottom surface of the substrate-to-be-processed supportingmember 8. An opening part is formed at a central portion of the fifthheating unit 7 e. A pole 8 d supporting the substrate-to-be-processedsupporting member 8 is inserted through the opening part.

The plate-like heat-generating member forming the fifth heating unit 7 emay be a film resistance heater formed into a disk shape, or a linearresistance heater densely arranged on a plane. When a linear resistanceheater is used, a linear resistance heater of low metal impurity may besealed into ceramics such as quartz. For example, a linear resistanceheater such as a carbon wire made of high purity carbon may be arrangedin a coil pattern or a switchback pattern in a disk member made ofquartz (quartz plate) having a thickness of about 8 mm. In addition,quartz may be interposed between adjacent linear resistance heaters. Inthe case, the linear resistance heaters may be arranged between spiralpartition walls made of quartz. It is preferable that the plate-likeheat-generating member has a size not smaller than that of the substrateto be processed W, in order to secure high heat-retention effectiveness.

When the fifth heating unit 7 e is formed by a plurality of resistanceheaters, each resistance heater may have a block shape or any othershape, and the resistance heaters may be arranged along the bottomsurface of the substrate-to-be-processed supporting member 8. Theplurality of resistance heaters may be arranged in such a manner thattheir heating temperatures are uniform.

When a plate-like heat-generating member is used, for example, columnsmade of quartz may be provided at three peripheral positions at the sameintervals in a circumferential direction on the lower surface of theplate-like heat-generating member. The columns are fixed to thereaction-tube lower lid. One of the three columns may be formed by atubular member. Both end portions of the linear resistance-heaters aregathered at one peripheral portion of the plate-like heat-generatingmember. A pair of feeder members connected to the resistance heaters,for example a pair of feeder wires of the same material as theresistance heaters, is inserted through a thin quartz tube, and thequartz tube is inserted through the tubular member (column). Then, thefeeder wires may be arranged out of the lid. When the feeder wires areconnected to an outside electric power source, the resistance heatersgenerate heat. Residual two columns may be tubular members or rodmembers.

In addition, it is preferable that a heat reflector 12 having an openingpart at a central portion thereof is arranged under the fifth heatingunit 7 e formed by a plate-like heat-generating member via a gap inparallel with the plate-like heat-generating member 7 e. The heatreflector 12 reflects heat generated by the plate-like heat-generatingmember and prevents downward heat dissipation. The number of providedheat reflectors 12 may be single or plural. It is preferable that theplate-like heat-generating member and the heat reflector 12 havesubstantially the same shape. The plate-like heat-generating member andthe heat reflector 12 are fixed to the reaction-tube lower lid 4, asshown in FIG. 1.

The heat reflector 12 may be made of, for example, opaque quartz orsilicon carbide.

The five kinds of heating units 7 a to 7 e of the present embodiment areindependently controlled by a controlling unit not shown (appropriatelysupplied electric power), so that respective heat values thereof arecontrolled. Thus, temperature distribution in the reaction tube 3 may bemade uniform.

According to the above heating units 7 a to 7 e, the temperature controlis easy, and particle generation may be prevented effectively. Inaddition, since the thermal capacity is small, the embodiment issuitable for rapid heating and rapid cooling, and unevenness in heatingthe substrates to be processed such as the silicon wafers may beremarkably improved.

In the present embodiment, the five heating units 7 a to 7 e heat thesubstrates to be processed W arranged in the reaction tube 3. Theheating units 7 a to 7 e cooperate to make temperature distributionwithin the surfaces of the substrates to be processed W as uniform aspossible. Additional other heating units may be used as far as volumelimitation of the heating-furnace body 1 permits.

Second Embodiment

In the present embodiment, additionally to the thermal processing unitof the first embodiment, a temperature measuring unit for measuring athermal process temperature of the substrates to be processed isprovided. FIG. 5 schematically shows a thermal processing unit accordingto the present embodiment. As shown in FIG. 5, in the presentembodiment, three temperature measuring units are arranged. In FIG. 5, acomponent having the same function as in FIG. 1 is represented by thesame numeral sign, and the detailed explanation thereof is omitted.

Hereinafter, the temperature measuring units that are features of thepresent embodiment are mainly explained.

(First Temperature Measuring Unit)

The first temperature measuring unit 9 a has: a main-shaft portionconsisting of a straight hollow tubular member; and a branch portionbranched from the main-shaft portion at a middle position thereof in aperpendicular direction thereto. A known temperature measuring devicesuch as a thermocouple is sealed in the branch portion. Herein, it ispreferable that a plurality of temperature measuring devices is sealedtherein in order to measure temperatures at a plurality of positions atthe same time. For example, the hollow tubular member is made ofceramics such as silicon carbide or quartz.

The temperature measuring unit 9 a is arranged perpendicular to thereaction-tube lower lid 4. Specifically, the temperature measuring unit9 a is inserted through a vertical hole formed in the reaction-tubelower lid 4 in such a manner that airtightness can be maintained and thetemperature measuring unit 9 a can rotate around an axis perpendicularto the reaction-tube lower lid 4. That is, as seen from FIG. 6 that is atop plan view of a section of the reaction tube 3, the branch portion ofthe temperature measuring unit 9 a is capable of pivoting between anarrangement state (position A) wherein a tip end thereof is located inthe vicinity of a center of the ceiling plate 8 a of thesubstrate-to-be-processed supporting member 8 and an arrangement state(position B) wherein the tip end thereof is located out of the ceilingplate 8 a of the substrate-to-be-processed supporting member 8. Then,when the temperature measuring unit 9 a is located at the position A,the plurality of temperature measuring devices arranged in the branchportion of the temperature measuring unit 9 a can measure temperaturesat a plurality of positions on the surfaces of the substrates to beprocessed. Thus, temperature distribution within the surfaces of thesubstrates to be processed can be monitored. When the branch portion ofthe temperature measuring unit is moved to the position B, temperaturesat peripheral positions of the substrates to be processed can bemeasured.

It is preferable that a plurality of branch portions is branched fromthe main-shaft portion in the temperature measuring unit 9 a, in orderto enhance temperature measurement precision. Especially, it ispreferable that they are arranged in at least three positions includingan upper gap, a middle gap and a lower gap of the plurality ofsubstrates to be processed W.

The temperature measuring unit 9 a in the present embodiment isremovably arranged in the reaction tube via the hole formed in thereaction-tube lower lid 4. When heating characteristics of the thermalprocessing unit are evaluated at setting up the thermal processing unitor the like, surface temperatures of the substrates to be processed asobjects to be heated have to be measured. For that purpose, thetemperature measuring unit 9 a is mainly used. On the other hand, in asteady operation of the thermal processing unit, necessity to use thetemperature measuring unit 9 a is small. Thus, in a steady operation ofthe thermal processing unit, the temperature measuring unit 9 a can betaken out from the thermal processing unit so that the temperaturemeasuring unit 9 a doesn't disturb the thermal processing step.

In addition, it is preferable that an upper end of the main-shaftportion of the hollow tubular member is removably supported by theceiling plate 8 a of the substrate-to-be-processed supporting member 8.Thus, temperature measurement can be stably conducted without vibrationof the main-shaft portion of the hollow tubular member during noperation of the thermal processing unit.

(Second Temperature Measuring Unit)

The second temperature measuring unit 9 b is a temperature measuringdevice such as a thermocouple sealed in a ceramics hollow member such asa quartz tube or a silicon carbide tube, similarly to the firsttemperature measuring unit 9 a. The second temperature measuring unit 9b extends upward along a inside wall of the reaction tube 3 from areaction-tube lower flange 3 d, and is bent at an upper portion of thereaction tube 3 toward a center of the reaction tube 3. A plurality oftemperature measuring devices is sealed at a plurality of positions ofthe hollow tubular member. The second temperature measuring unit 9 boperates in a steady operation of the thermal processing unit in orderto measure temperatures in the vicinity of the substrates to beprocessed. Thus, the operating condition in the steady operation of thethermal processing unit can be known (detected).

(Third Temperature Measuring Unit)

The third temperature measuring unit 9 c is also formed by sealing atemperature measuring device into a ceramics hollow member, similarly tothe first and second temperature measuring units 9 a and 9 b. The thirdtemperature measuring unit 9 c is arranged in a gap formed between theheating-furnace body 1 and the reaction tube 3, in parallel with thelongitudinal direction of the reaction tube 3. A plurality oftemperature measuring devices is arranged in the hollow tubular memberof the third temperature measuring unit 9 c. Thus, temperaturemeasurement with high precision is possible. The third temperaturemeasuring unit 9 c operates in a steady operation of the thermalprocessing unit in order to measure peripheral temperatures of thereaction tube 3. Thus, the operating condition of the thermal processingunit can be known (detected).

In the present embodiment, the temperature measuring units 9 a to 9 care arranged in the unit of the first embodiment. Thus, temperaturemeasurement with high precision is conducted so that the operatingcondition of the thermal processing unit can be known (detected). Then,based on information about the temperature distribution in the reactiontube 3 measured by the temperature measuring units 9 a to 9 c, theheating units 7 a to 7 e may be controlled, so that the temperatures ofthe substrates to be processed W may be made uniform.

In the second embodiment, the three temperature measuring units 9 a to 9c are provided. However, if at least one of the temperature measuringunits is adopted, the effect may be expected. It is most preferable thatall the three temperature measuring units are provided. In addition,additional other temperature measuring units may be arranged unless theydisturb the operation of the thermal processing unit.

Third Embodiment

In the present embodiment, additionally to the thermal processing unitof the first embodiment, a cooling mechanism for forcibly cooling thereaction tube 3 is provided. FIG. 7 schematically shows a thermalprocessing unit according to the present embodiment. In FIG. 7, acomponent having the same function as in FIG. 1 is represented by thesame numeral sign, and the detailed explanation thereof is omitted.

Hereinafter, the cooling mechanism that is a feature of the presentembodiment is mainly explained.

As seen in FIG. 7, the cooling mechanism consists of: a cooling-mediumsupplying port 13 formed at a lower portion of the wall of theheating-furnace body 1; a cooling-medium supplying system having acooling-medium supplying unit connected to the cooling-medium supplyingport 13 and not shown; and a cooling-medium discharging port 14 formedat the heating-furnace lid 2.

A medium such as cooling air is pressed from the cooling-mediumsupplying unit into the heating-furnace body 1 via the cooling-mediumsupplying port 13 by means of a compressing unit such as a pump. Thus,the reaction tube 3 is cooled forcibly. It is sufficient that at leastone cooling-medium supplying port 13 is provided. However, preferably, aplurality of cooling-medium supplying ports 13 is provided in order touniformly cool the periphery of the reaction tube.

By means of the cooling mechanism, cooling period of the thermalprocessing unit can be shortened, and throughput of the thermalprocessing unit can be enhanced.

Fourth Embodiment

In the fourth embodiment, additionally to the thermal processing unit ofthe first embodiment, provided are the temperature measuring unit 8explained in the second embodiment, the cooling mechanism 13, 14explained in the third embodiment, and a temperature controlling unit 15for controlling a temperature in the vicinity of a connecting portion ofthe gas-discharging port 6 at the upper portion of the reaction tube 3and the gas-discharging pipe 16.

FIG. 8 schematically shows a thermal processing unit according to thepresent embodiment. In FIG. 8, a component having the same function asin FIG. 1, FIG. 5 or FIG. 7 is represented by the same numeral sign, andthe detailed explanation thereof is omitted.

Hereinafter, the temperature controlling unit for controlling atemperature in the vicinity of a connecting portion of thegas-discharging port and the gas-discharging pipe, which is a feature ofthe present embodiment, is mainly explained.

As described above, the thermal processing unit of the presentembodiment has: the heating-furnace body 1; the five kinds of heatingunits 7 a to 7 e; the three kinds of temperature measuring units 9 a to9 c: and the cooling mechanism 13, 14. In this unit, the gas-dischargingport 6 and the bent portion 3 c extending form the narrow-diameterportion 3 b at the upper portion of the reaction tube 3 protrude fromthe heating-furnace body 1. Thus, temperatures at these portions arelower than the temperature in the heating-furnace body 1. Then, if thetemperatures at these portions are relatively low, a reaction gassupplied into the reaction tube 3 and/or a generated gas generated inthe reaction tube 3 are cooled at these portions, so that deposit or animpurity film is formed. If the undesired film grows, it graduallybecomes easier for the film to peel off. When the film (deposit) peelsoff because of thermal stress or the like, the film becomes particles,falls in the reaction tube 3, and contaminates the substrates to beprocessed W such as the silicon wafers. For avoiding this problem, thetemperature at the upper area of the reaction tube 3 is controlled sothat generation of deposit that may cause particle contamination isprevented.

As the temperature controlling unit 15 arranged in the vicinity of theconnecting portion of the gas-discharging port 6 and the gas-dischargingpipe 16, a heat-insulating material or a resistance heater may be used.In particular, it is preferable that a resistance heater is used as thetemperature controlling unit 15 in order to enhance the effect ofheat-retaining.

In addition, the temperature of the gas-discharging-pipe connectingportion is preferably equal to a wafer process temperature (processingtemperature). Thus, uniformity of temperatures of the wafers arranged inan upper portion of the reaction tube 3 can be remarkably improved. Inaddition, in the case, the number of dummy wafers, which are generallyarranged on the uppermost stages of the substrate-to-be-processedsupporting member for the uniformity of temperatures of the wafers, canbe reduced. Thus, the height of the heating unit may be reduced.

In FIG. 9, the temperature controlling unit 15 is formed by a pluralityof divided components. However, the components may be integral.

Preferably, the resistance heater is a heater made of a carbon wireincluding fewer impurities. In addition, the heating unit may be aflexible heater that can be wound around the gas-discharging-pipeconnecting portion having a complicated shape, or may be a heater thathas been formed in advance into a shape to be fitted with the shape ofthe gas-discharging-pipe connecting portion.

As the flexible heater, a carbon wire may be used, the carbon wireincluding: a wire-like heater-main-body formed by braiding a pluralityof carbon fibers; and metal terminals attached to both ends of theheater-main-body. Such a flexible heater may be installed by windingaround the gas-discharging-pipe connecting portion of the upper portionof the reaction tube 3.

Alternatively, as the previously-shaped heater, a seal heater may beused, the seal heater being formed by forming the above carbon wire intoa predetermined shape, sandwiching the carbon wire between two quartzglass plates, and heating the two quartz glass plates to melt them andfix them to the carbon wire in a predetermined shape. The seal heatermade of quartz glass has only very low possibility of impuritiescontamination, which is suitable for the present invention.

In any case, in order to avoid impurities contamination, it ispreferable to design the unit in such a manner that a temperaturecontrolling unit may be easily arranged in the unit.

As shown in FIG. 8, it is preferable that the gas-discharging-pipeconnecting portion 6 is bent at an angle of about 90 degrees toward alateral direction of the reaction tube 3. If the temperature of theconnecting portion of the gas-discharging-pipe connecting portion 6 andthe gas-discharging pipe 16 is lower than that of the main body of thereaction tube 3, the reaction gas and/or the generated gas remaining inthe exhaust gas are cooled to be solidified in that portion, so thatimpurity films may be formed in that portion. Then, the impurity filmsmay be peeled off to generate particles. Thus, if the connecting portionis located just above the substrate-to-be-processed supporting member,the particles generated at the connecting portion may fall directly onthe substrate-to-be-processed supporting member, which may causecontamination of the silicon wafers. Therefore, it is preferable thatthe gas-discharging-pipe connecting portion 6 is bent, in order for theparticles not to fall directly on the substrate-to-be-processedsupporting member, even if the particles are generated in the connectingportion of the gas-discharging-pipe connecting portion 6 and thegas-discharging pipe 16.

In addition, as the gas-discharging-pipe connecting portion 6 is bent,radiation heat from the resistance heater 7 that heats the reaction tube3 doesn't directly reach a flange 17 a (see FIG. 9) formed at an endportion of the gas-discharging-pipe connecting portion 6 and thegas-discharging pipe 16. Thus, temperature controls for their membersare easy. In that view, preferably, the end portion of thegas-discharging-pipe connecting portion 6 extends nearly to an extensionline of the lateral surface of the main body of the reaction tube 3.

As shown in FIG. 9, the flange 17 a formed at the end portion of thegas-discharging-pipe connecting portion 6 is closely and hermeticallyfixed to a flange 17 b formed at the gas-discharging pipe 16, via anO-ring 18 made of an elastomer such as a fluorine resin.

A heat-resistant temperature of the O-ring 18 (elastomer) is usuallyabout 300° C. Thus, if the O-ring 18 is heated to a high temperature,the quality of the O-ring 18 may be deteriorated, that is, the sealingperformance may be deteriorated. In order to prevent the deteriorationof the sealing performance, it is necessary to control a temperature ofa portion close to the O-ring 18. In the embodiment, a fluid way 19 fortemperature control is formed at the flange 17 b, and a fluid fortemperature control, such as cooling water, flows through the fluid way19. Thus, the temperature of the flange 17 b is adapted to be controlledsuitably. In addition, if a temperature controlling unit 15 like aresistance heater is arranged along a side wall of the flange 17 b ofthe gas-discharging pipe 16, the temperature distribution can becontrolled more accurately.

The gas-discharging pipe 16 connected to the end portion of thegas-discharging-pipe connecting portion 6 is connected to a suction unitsuch as a vacuum pump, not shown. Thus, a vacuum can be created in thereaction tube 3, and the remaining reaction gas, the generated gas andthe like can be discharged from the reaction tube 3.

In the embodiment, a temperature controlling unit 15 is also arrangedaround the gas-discharging pipe 16. Thus, more accurate temperaturecontrol can be achieved. An electric heater is preferably used as thetemperature controlling unit 15, because the control of the electricheater is easy. It is preferable that the temperature of thegas-discharging pipe 16 is controlled within a range of 150 to 300° C.More preferable temperature of the gas-discharging pipe 16 is 200° C. Bymeans of the above temperature control, even if the exhaust (discharged)gas from the reaction tube 3 passes through the gas-discharging pipe 16,it can be prevented that any impurity film is generated as unnecessarydeposit in the gas-discharging pipe 16.

The exhaust gas discharged from the gas-discharging pipe 16 is cooled bya trap, not shown, which is connected to the gas-discharging pipe 16 andhas cooling fins or the like. Thus, the exhaust gas (remaining reactiongas, generated gas or the like) discharged from the reaction tube 3 maybe solidified and trapped thereby. It is preferable that the trap isarranged between a flange (not shown) at the other end of thegas-discharging pipe 16 and a vacuum pump (not shown) connected to thegas-discharging pipe 16.

As described above, according to the thermal processing unit of theembodiment, the temperatures of the respective members are positivelycontrolled by means of: the temperature controlling unit 15 forcontrolling the temperature of the gas-discharging-pipe connectingportion 6; the fluid-flowing tunnel for temperature control 19 buried inthe flange 17 b of the gas-discharging pipe 16; the temperaturecontrolling unit 15 arranged for the side-wall portion of the flange 17b of the gas-discharging pipe 16; and the temperature controlling unit15 arranged along the gas-discharging pipe 16. Thus, in the vicinitiesof these members, it can be effectively prevented that an impurity filmas unnecessary deposit is generated and that particles are generatedfrom the impurity film.

In the above embodiments of the invention, the silicon wafer isexplained as an object to be processed. However, the object to beprocessed is not limited to the silicon wafer, but may be a LCDsubstrate or a glass substrate.

1. A thermal processing unit comprising: a heating-furnace body whoseupper end has an opening, a reaction tube consisting of a single tubecontained in the heating-furnace body, a gas-discharging-unit connectingportion formed at an upper portion of the reaction tube, thegas-discharging-unit connecting portion having a narrow diameter, asubstrate-to-be-processed supporting member for supporting a substrateto be processed, contained in the heating-furnace body, and a heatingunit for heating the substrate to be processed supported by thesubstrate-to-be-processed supporting member, wherein the heating unithas: a first heating portion arranged around the reaction tube, a secondheating portion arranged around the gas-discharging-unit connectingportion, a third heating portion arranged around an upper portion of thereaction tube, a fourth heating portion arranged around a lower portionof the reaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member, wherein the first heatingportion is formed by a plurality of linear heat-generating members,which are arranged in parallel with a longitudinal direction of thereaction tube.
 2. A thermal processing unit according to claim 1,wherein the linear heat-generating member is formed by sealing aresistance heater into a hollow tubular member made of ceramics.
 3. Athermal processing unit according to claim 2, wherein the ceramics isquartz.
 4. A thermal processing unit comprising: a heating-furnace bodywhose upper end has an opening, a reaction tube consisting of a singletube contained in the heating-furnace body, a gas-discharging-unitconnecting portion formed at an upper portion of the reaction tube, thegas-discharging-unit connecting portion having a narrow diameter, asubstrate-to-be-processed supporting member for supporting a substrateto be processed, contained in the heating-furnace body, and a heatingunit for heating the substrate to be processed supported by thesubstrate-to-be-processed supporting member, wherein the heating unithas: a first heating portion arranged around the reaction tube, a secondheating portion arranged around the gas-discharging-unit connectingportion, a third heating portion arranged around an upper portion of thereaction tube, a fourth heating portion arranged around a lower portionof the reaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member, wherein the first heatingportion is formed by a plurality of U-shaped heat-generating members,which are arranged in parallel with a longitudinal direction of thereaction tube.
 5. A thermal processing unit comprising: aheating-furnace body whose upper end has an opening, a reaction tubeconsisting of a single tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member, whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member, wherein the second heating portion is formed by alinear heat-generating member, which is arranged in a spiral pattern. 6.A thermal processing unit comprising: a heating-furnace body whose upperend has an opening, a reaction tube consisting of a single tubecontained in the heating-furnace body, a gas-discharging-unit connectingportion formed at an upper portion of the reaction tube, thegas-discharging-unit connecting portion having a narrow diameter, asubstrate-to-be-processed supporting member for supporting a substrateto be processed, contained in the heating-furnace body, and a heatingunit for heating the substrate to be processed supported by thesubstrate-to-be-processed supporting member, wherein the heating unithas: a first heating portion arranged around the reaction tube, a secondheating portion arranged around the gas-discharging-unit connectingportion, a third heating portion arranged around an upper portion of thereaction tube, a fourth heating portion arranged around a lower portionof the reaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member, wherein the third heatingportion is formed by a linear heat-generating member, which is arrangedin a spiral pattern.
 7. A thermal processing unit comprising: aheating-furnace body whose upper end has an opening, a reaction tubeconsisting of a single tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member, whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member, wherein the third heating portion is formed by alinear heat-generating member, which is arranged in a switchbackpattern.
 8. A thermal processing unit comprising: a heating-furnace bodywhose upper end has an opening, a reaction tube consisting of a singletube contained in the heating-furnace body, a gas-discharging-unitconnecting portion formed at an upper portion of the reaction tube, thegas-discharging-unit connecting portion having a narrow diameter, asubstrate-to-be-processed supporting member for supporting a substrateto be processed, contained in the heating-furnace body, and a heatingunit for heating the substrate to be processed supported by thesubstrate-to-be-processed supporting member, wherein the heating unithas: a first heating portion arranged around the reaction tube, a secondheating portion arranged around the gas-discharging-unit connectingportion, a third heating portion arranged around an upper portion of thereaction tube, a fourth heating portion arranged around a lower portionof the reaction tube, and a fifth heating portion arranged under thesubstrate-to-be-processed supporting member, wherein the fourth heatingportion is formed by a linear heat-generating member, which is arrangedin a spiral pattern that is seen as rectangular in a circumferentialdirection of the reaction tube.
 9. A thermal processing unit comprising:a heating-furnace body whose upper end has an opening, a reaction tubeconsisting of a single tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member, whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member, wherein the fourth heating portion is formed by alinear heat-generating member, which is arranged in a switchbackpattern.
 10. A thermal processing unit comprising: a heating-furnacebody whose upper end has an opening, a reaction tube consisting of asingle tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member, whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member, wherein the fifth heating portion is formed by aplate-like heat-generating member.
 11. A thermal processing unitaccording to claim 10, wherein the plate-like heat-generating member isformed by sealing a resistance heater into a hollow plate-like membermade of ceramics.
 12. A thermal processing unit comprising: aheating-furnace body whose upper end has an opening, a reaction tubeconsisting of a single tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, and a heating unit for heating the substrate to be processedsupported by the substrate-to-be-processed supporting member, whereinthe heating unit has: a first heating portion arranged around thereaction tube, a second heating portion arranged around thegas-discharging-unit connecting portion, a third heating portionarranged around an upper portion of the reaction tube, a fourth heatingportion arranged around a lower portion of the reaction tube, and afifth heating portion arranged under the substrate-to-be-processedsupporting member, wherein the second heating portion is supported in amovable manner in a horizontal direction.
 13. A thermal processing unitcomprising: a heating-furnace body whose upper end has an opening, areaction tube consisting of a single tube contained in theheating-furnace body, a gas-discharging-unit connecting portion formedat an upper portion of the reaction tube, the gas-discharging-unitconnecting portion having a narrow diameter, a substrate-to-be-processedsupporting member for supporting a substrate to be processed, containedin the heating-furnace body, a heating unit for heating the substrate tobe processed supported by the substrate-to-be-processed supportingmember, a reaction-tube lower lid that seals a lower portion of thereaction tube and holds airtightness in the reaction tube, and atemperature measuring unit formed by sealing a plurality of temperaturemeasuring members into a hollow tubular member, wherein the hollowtubular member is arranged in a gap between the heating-furnace body andthe reaction tube.
 14. A thermal processing unit comprising: aheating-furnace body whose upper end has an opening, a reaction tubeconsisting of a single tube contained in the heating-furnace body, agas-discharging-unit connecting portion formed at an upper portion ofthe reaction tube, the gas-discharging-unit connecting portion having anarrow diameter, a substrate-to-be-processed supporting member forsupporting a substrate to be processed, contained in the heating-furnacebody, a heating unit for heating the substrate to be processed supportedby the substrate-to-be-processed supporting member, a reaction-tubelower lid that seals a lower portion of the reaction tube and holdsairtightness in the reaction tube, a second temperature measuring unitformed by sealing a plurality of temperature measuring members into asecond hollow tubular member, and a third temperature measuring unitformed by sealing a plurality of temperature measuring members into athird hollow tubular member, wherein at least a portion of the secondhollow tubular member extends horizontally from an upper portion of thereaction tube, and at least a portion of the third hollow tubular memberis arranged in a gap between the heating-furnace body and the reactiontube.
 15. A thermal processing unit comprising: a heating-furnace bodywhose upper end has an opening, a reaction tube consisting of a singletube contained in the heating-furnace body, a gas-discharging-unitconnecting portion formed at an upper portion of the reaction tube, thegas-discharging-unit connecting portion having a narrow diameter, asubstrate-to-be-processed supporting member for supporting a substrateto be processed, contained in the heating-furnace body, a heating unitfor heating the substrate to be processed supported by thesubstrate-to-be-processed supporting member, a reaction-tube lower lidthat seals a lower portion of the reaction tube and holds airtightnessin the reaction tube, a second temperature measuring unit formed bysealing a plurality of temperature measuring members into a secondhollow tubular member, and a third temperature measuring unit formed bysealing a plurality of temperature measuring members into a third hollowtubular member, wherein the heating unit has: a first heating portionarranged around the reaction tube, a second heating portion arrangedaround the gas-discharging-unit connecting portion, a third heatingportion arranged around an upper portion of the reaction tube, a fourthheating portion arranged around a lower portion of the reaction tube,and a fifth heating portion arranged under the substrate-to-be-processedsupporting member, at least a portion of the second hollow tubularmember extends horizontally from an upper portion of the reaction tube,and at least a portion of the third hollow tubular member is arranged ina gap between the heating-furnace body and the reaction tube.
 16. Athermal processing unit according to claim 15, wherein a temperaturecontrolling unit is provided around the gas-discharging-unit connectingportion.
 17. A thermal processing unit according to claim 16, whereinthe temperature controlling unit is a heat-insulating material.
 18. Athermal processing unit according to claim 16, wherein the temperaturecontrolling unit is a resistance heater.
 19. A thermal processing unitaccording to claim 18, wherein the temperature controlling unit hasflexibility.
 20. A thermal processing unit according to claim 18,wherein the temperature controlling unit is shaped in advance.
 21. Athermal processing unit according to claim 15, wherein thegas-discharging unit is a gas-discharging pipe whose end portion has aflange, a flange is formed at an end portion of the gas-discharging-unitconnecting portion, and the flange at the end portion of thegas-discharging-unit connecting portion and the flange at the endportion of the gas-discharging pipe are hermetically connected to eachother by means of a sealing unit.
 22. A thermal processing unitaccording to claim 21, wherein the temperature controlling unit has afluid hole provided in the flange.